1. Field of the Invention
The present invention relates in general to an in-line filter device connected to a compressed air line, and more particularly to such an in-line compressed air filter device having an improved structural arrangement, which is capable of efficiently separating or removing liquid or vapor particles from the compressed air, such as water and oil which are contained therein.
2. Discussion of the Prior Art
Conduits used for supplying compressed air to various pneumatically operated components employed in various factories, atomic plants and medical equipment, for example, are generally provided with an in-line filter device or vapor trap assembly for removing water and-or oil vapor contained in a stream of the compressed air, for the purpose of protecting the pneumatic components or improving the performance of those components.
A type of such an in-line filter device for compressed air, adapted to minimize vapor and/or liquid particles contained in the compressed air, has been disclosed in U.S. Pat. No. 4,487,618 to David O. Mann. The disclosed filter device includes a vaporizer cartridge as first filter means having a suitable first packing or pad inside a sleeve thereof, and another vaporizer cartridge as second filter means having a suitable second packing or pad inside a sleeve thereof. The first and second filter means are disposed parallel with each other, so as to extend in the vertical direction from a base which provides an air-tightly enclosed trap structure having a suitable volume capacity, such that each of the first and second filter means communicates with an enclosed volume or trap chamber formed within the trap structure. The compressed air is directed to the trap chamber through the first filter means from an intake or inlet conduit, so that vapor (oil vapor) and/or liquid particles contained in the compressed air are condensed or coalesced into droplets, whereby the vapor and/or liquid particles are separated from the compressed air, and the droplets are captured within the trap chamber. Subsequently, the compressed air from which the vapor and/or liquid particles have been separated is directed to an outlet conduit through the second filter means from the trap chamber, so that any remaining liquid particles are vaporized. Thus, the amount of the vapor and/or liquid particles entrained in the air entering the outlet conduit is minimized.
In the in-line filter device as described above, the first packing of the first filter means is a wound wire mesh fabric formed of stainless steel fibers, while second packing of the second filter means is a wound fabric material formed of cotton fibers or other absorbing materials. However, such wound packings may have a gap or clearance between the inner circumferential surfaces of the filter sleeves and the outer circumferential surfaces of the packings, depending upon the winding condition of the fabrics of the packings. Therefore, the compressed air flowing through the thus formed gap or clearance potentially existing with the packings may be delivered to the outlet conduit, without removal of oil and/or liquid particles from the air during passage thereof through first and second filter means.
To overcome such a drawback, the assignee of the present invention has proposed an in-line filter device which assures improved efficiency of removal of the liquid particles from the compressed air, as disclosed in Japanese Utility Model Application No. 2-124392. The disclosed filter device includes a suitable cylindrical foam member disposed within the cylindrical sleeve of the second filter means such that the foam member is on the downstream side of the second packing, so as to further remove the remaining liquid particles contained in the compressed air which has passed through the first and second packings.
However, the thus constructed in-line filter device is still incapable of removing a sufficient amount of liquid particles, and thus incapable of delivering the compressed air free of oil and/or liquid particles to the outlet conduit. Further, the in-line filter device wherein the first and second filter means are disposed side and by side parallel to each other, each having an independent cylindrical structure standing on an air tightly enclosed trap structure, tends to be comparatively large sized. However, it is required to construct such an in-line filter device as compact as possible. In this sense, there still remains room for improvement in the construction of an in-line filter device of the type a described above.